The Twilight Saga Breaking Dawn Part 1 discussion

So, what bodily fluids in a vampire are toxic. I know that they cant keep contacts in for more than a few hours because they dissolve. Ive read the Twilight books but its been years and I havent gone back for a re-read. Bella just annoyed me the whole time anyways and I only finished the series because I had started it. Now, my question is: If vampire fluids are toxic then how can Bella and Edward kiss? Would'nt their wedding night be somewhat... corrosive to Bella since she was still human at the time?